The NSW government was warned last year that the cost of building its flagship rail line between central Sydney and Parramatta risked ballooning to almost $27 billion – nearly $3 billion more than earlier internal estimates – and opening three years late.

The forecast for Metro West was made about eight months ago, before the government committed to an extra station at Pyrmont, which will add hundreds of millions to the final cost of Australia’s largest transport project.

The Metro West rail line will run underground from central Sydney to Westmead.CREDIT:NICK MOIR

Confidential documents which contain modelling by Sydney Metro reveal for the first time the estimated cost of the project and that the government has been scrambling to find ways to reduce costs.

Sydney Metro, which is delivering the project, estimated the underground rail line would open to passengers in early 2033, three years later than the government has said publicly.

The documents show NSW Treasury has put pressure on Sydney Metro to rein in costs. Early last year, a cash restraint was imposed on the project as Sydney Metro revised the delivery strategy for the rail line, including the cost which it estimated at the time at $26.6 billion. The documents state that this was an increase of nearly $3 billion.

Unlike other new rail lines, the government has not released an expected cost for Metro West, which is the third stage of a metro rail network.

The documents show the estimated cost of underground stations alone for Metro West range from about $640 million for the CBD and $600 million for North Strathfield, to about $390 million for the Bays Precinct at Rozelle and $350 million for Five Dock. The figures include so-called escalation costs.

Transport Minister Andrew Constance said the government would not have the final price for Metro West until the last contract was signed.

“I am not going to comment about an internal working document of the Department which does not reflect a final decision. There are multiple contracts to be signed and any number is speculative in nature until we get that final contract price,” he said.

“This project will be built in 10 years, not 15, and we’ve already started building it.”

Transport Minister Andrew Constance says he will not have a final cost until the last contract for Metro West is signed.CREDIT:WOLTER PEETERS

Despite the internal modelling last year, the government said the timeframe for Metro West to open by 2030 had not changed, adding that “agencies are constantly optimising delivery schedules for major projects such as this one”.

But Labor leader Jodi McKay said it was not a surprise that Metro West was running late and massively over budget given the cost blowouts in the government’s other transport projects.

“At the last election, Andrew Constance committed to fast-tracking its delivery. Instead, this government has let it fall another three years behind,” she said.